1. Field of the Invention
The present invention relates to an improved structure of a connector unit having a front holder.
2. Description of the Related Art
In a conventional connector unit 3 which includes a front holder 2 designed to cover a connector housing 1 as shown in FIGS. 7 and 8, when any of female metal terminals (hereinafter referred to as xe2x80x9cterminalxe2x80x9d) 4, 5 has become defective, it has been common that the terminal is drawn out from the connector unit 3 employing a draw jig 7 having an inserting portion 6 which is in a rectangular shape in cross section as shown in FIG. 9.
A structure of the connector unit 3 will be explained hereunder;
The terminals 4, 5 are inserted into terminal receiving chambers 8 of the connector housing 1 from the back. Each of the inserted terminals 4, 5 is locked by a lance 10 which is abutted against a box-like portion forming a contact portion of the terminal to prevent a so-called backward withdrawal of the terminal, and firmly positioned in the connector housing.
On the other hand, the front holder 2 is coupled to a front of the connector housing 1 so that an interior of the connector unit 3 is completely shut from an exterior.
The front holder 2 of the connector unit 3 thus assembled is provided with terminal insertion holes 11 through which mating male terminals (not shown) are adapted to be inserted for electrical connection with the terminals 4, 5. In addition, draw jig holes 12 in a rectangular shape similar to the inserting portion 6 of the draw jig 7 are formed in the front holder 2 adjacently to the terminal insertion holes 11.
In case where the inserted terminals 4, 5 are electrically defective, or caulking strength at press fitted parts 9 of the terminals 4, 5 is weak, and so on, the terminals 4, 5 must be disengaged from the connector unit 3 to be replaced with new terminals, or to readjust the caulking strength.
In such cases, the draw jig 7 is inserted into the terminal receiving chamber 8 through the draw jig hole 12. A distal end of the draw jig 7 has a rather pointed shape like a bow of a ship, as shown in FIG. 9. In a first step, the distal end is abutted against a distal end of the lance 10 formed of synthetic resin (FIG. 10A), and by further pushing the draw jig 7, the lance 10 is forced to be elastically deformed downward from a state in FIG. 10B to a state in FIG. 10C thereby to disengage the lance 10 from the terminal.
In this state, the defective terminal can be drawn out backward from the terminal receiving chamber 8 and readjusted.
However, when the draw jig 7 is inserted into the draw jig hole 12 in a direction of an arrow A as shown in FIG. 12, and the lance 10 is forced to be elastically deformed downward to be disengaged as shown in FIG. 10, a reaction force acts on the inserting portion 6 of the draw jig 7. Conventionally, during the terminal withdrawing operation, the reaction force has been received only by a partition wall 14 which constitutes a lower edge of tapered edges of the terminal insertion hole 11, existing between the draw jig hole 12 and the terminal insertion hole 11, and which is short in depth dimension. Accordingly, the partition wall 14 receives an upward deforming force from the draw jig 7 and apts to be damaged by the draw jig 7. Moreover, when the mating terminal 15 is inserted into the terminal insertion hole 11 in a direction of an arrow B, it has been concerned that the mating terminal T may be abutted against the partition wall 14 thereby damaging the partition wall 14.
If the partition wall 14 has been broken or damaged in this manner, it has been concerned that the draw jig 7 may intrude into the terminal insertion hole 11, thereby causing a fatal damage on the female terminal 4 or 5.
Further, since the draw jig hole 12 is in a rectangular shape similar to the shape of the distal end of the draw jig 7, there has been such fears that the draw jig 7 itself may be inserted into the draw jig hole 12 upside down, whereby the lance 10 is deformed toward the terminal 4, 5 resulting in a damage of the terminal, or the lance 10 may bite the terminal 4, 5 causing the-connector unit 3 itself to be defective.
In view of the above drawbacks, it is an object of the present invention to provide a connector unit having a front holder in which a guide support section is formed in the draw jig hole in the front holder, thereby to minimize damages or breakdowns of the metal terminals, the front holder, the connector housing, etc.
In order to attain the above described object, there is provided, according to a first aspect of the present invention, a connector unit having a front holder comprising;
a connector housing which includes at least one terminal receiving chamber into which a metal terminal is inserted from a back side, the metal terminal being locked by a lance for prevention of a backward withdrawal, and
a front holder coupled to the connector housing from a front side, the front holder being provided with at least one terminal insertion hole into which a mating terminal is adapted to be inserted from a front side so as to be connected with the metal terminal, and at least one draw jig hole through which a draw jig is inserted from a front side to force the lance to be elastically deformed thereby to disengage a lock between the lance and the metal terminal,
the draw jig hole adjacent to the terminal insertion hole being provided with a guide support section which can guide the draw jig to move back and forth, and bear a reaction force from the lance acting on the draw jig when the lance is disengaged.
According to a second aspect of the invention, the guide support section has a determined length in a direction of back and forth movement of the draw jig, whereby the lance can be smoothly disengaged by means of the draw jig.
According to a third aspect of the invention, the draw jig hole has a wall at an area adjacent to the terminal insertion hole.
According to a fourth aspect of the invention, the draw jig hole is composed of a main hole extending away from the terminal insertion hole and lateral holes extending laterally from the main hole, while the draw jig is formed in such a shape in cross section that the draw jig can be correspondingly inserted into the main hole and the lateral holes.
In the connector unit having the front holder according to the first aspect of the invention, the draw jig is guided by the guide support section to move back and forth, and the guide support section receives the reaction force from the lance acting on the draw jig.
In the connector unit having the front holder according to the second aspect of the invention, because the guide support section has a determined length in the moving direction of the draw jig, the draw jig can smoothly move back and forth.
In the connector unit having the front holder according to the third aspect of the invention, because the draw jig hole has the wall at the area adjacent to the terminal insertion hole, strength of the draw jig hole will be enhanced.
In the connector unit having the front holder according to the fourth aspect of the invention, because the draw jig hole is composed of the main hole extending away from the terminal insertion hole and the lateral holes extending laterally from the main hole, the draw jig will not be inserted upside down into the draw jig hole by mistake.